Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already carry readOnlyHint=true, so the description does not need to restate read-only safety. The GET /receipts/{id} endpoint reinforces the HTTP method but adds no behavioral detail beyond the annotation, such as error behavior or response format.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences front-load the action and scope, and the endpoint reference is useful context. Every word earns its place; there is no fluff or restatement of the schema.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter, read-only retrieval tool with no output schema, the description plus the input schema is sufficient. An agent knows the resource, the identifier, the HTTP endpoint, and the safe/read-only nature.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the one parameter is already documented as 'The resource id.' The description's 'by id' repeats this without adding validation rules, format, or source guidance, so it meets but does not exceed the baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Fetch'), a single resource ('a single receipt'), and the selection key ('by id'). This clearly distinguishes it from list_receipts and the other get_* siblings that target different resources.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Fetch a single receipt by id' establishes the clear condition for use: when an agent has a receipt ID and needs exactly one receipt. It doesn't explicitly contrast with list_receipts or other alternatives, but the singular scope gives clear context without exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.